A recent study of the world’s oceans has confirmed that levels of mercury have tripled since the onset of the industrial revolution, with human activity largely to blame.

Mercury Cycle – Photo Courtesy of Women of Water Blog

The amount of mercury within the world’s oceans has tripled since the onset of the industrial revolution as a direct result of human activity, according to a recent report published in the international science journal Nature.

Whilst marine biologists have long since suspected that the amount of mercury in our oceans is reaching critical levels, the damning report is the first time an in-depth analysis has been carried out.

After compiling the findings of five years of research, the team of scientists – lead by Carl Lamborg of the prestigious Woods Hole Oceanographic Institute in Massachusetts – was able to establish not only an accurate estimate of the amount of marine mercury within our oceans but also at what depths it can be found and why.

During eight research missions, the team collected thousands of water samples from all over the world – paying particular attention to the North and South Atlantic, the Pacific Ocean and the Southern Seas. Their analysis revealed that whilst the toxic metal is yet to penetrate the deeper water layers of our oceans, within the upper 100 meters, marine mercury has increased by a factor of 3.4 since the onset of the industrial revolution.

According to Lamborg, however, it won’t be long be long until even the deeper water layers are penetrated by the toxic metal. With no signs of humans turning their backs on burning fossil fuels – one of the main causes of mercury entering the environment – mankind is actually on track to emit as much mercury in the next 50 years as they did in the last 150 years – bad news for our marine ecosystems.

“You’re starting to overwhelm the ability of deep water formation to hide some of that mercury from us, with the net result that more and more of our emissions will be found in progressively shallower water,” Lamborg explained, in an interview with Nature.com. “That increases the odds that mercury levels in key food species will rise, increasing humans’ exposure.”

Scientists have long since warned about the effects of mercury, a substance proven to pose a particular threat to the earth’s marine ecosystems. After being released into the environment mercury often finds its way into the world’s waters, where it reacts to form methylmercury – an organic compound which is absorbed into the body at a much faster rate than inorganic mercury and which is at risk of entering the food chain

In this form, the metal is highly toxic to both humans and marine life alike. In some cases, the damage is already apparent. Simon Boxall, lecturer on ocean and Earth science at the University of Southampton highlights the Arctic as a region particularly at threat, describing how even the region’s top predators are feeling the effects of increased marine mercury.

“In the Arctic and Antarctic [where, due to unfavourable wind and tidal conditions, the process of the damage to marine life becoming apparent is faster], you will be starting to see some of this now,” he said. “But with deep-sea fishing in the tropics you will not see it yet, but you will see it within a hundred years.”

It’s not too late to make a difference, however. According to David Krabbenhoft, a geochemist with the US Geological Survey in Middleton, Wisconsin, the fact that the oceans are not uniformly contaminated is a sign of hope. “[The research] suggests that generational changes have been seen in the oceans’ mercury levels,” he explains. “If that’s the case we would expect them to undergo responses linked to reduced mercury outputs from mankind.”

Lamborg agrees. “It’s a cause for optimism and should make us excited to do something about it because we may actually have an impact.”

For more stories like this, head over to www.oceansandislands.org – a new e-magazine which combines insights into exemplary marine management with news and stories from the world of private islands.